1. Field of the Invention
The present invention relates to an optical device having optical members (such as light guides) which are held by a holding member (such as a sleeve) at the ends of the optical members, and also relates to an optical member (such as a light guide) which is used in combination with an external optical member.
2. Description of the Related Art
The optical contacting technique is a technique which is usually used for connecting tip ends of two optical fibers by making the end surfaces of the two optical fibers abut each other. According to the optical contacting technique, optical components such as optical fibers are joined by pressing the optical components together in such a manner that the optical components directly abut each other without interposition of another substance such as an adhesive between the optical components. Since the optical components directly abut each other in the optical contact, the optical contacting technique enables achievement of high optical propagation efficiency. FIG. 7 shows a cross section of a portion of a conventional optical device 100 in which an optical contact is used. As illustrated in FIG. 7, the optical fibers 1a and 1b are held by insertion of the optical fibers 1a and 1b into the ferrules 21 and 2b, and fixed by insertion of the near-tip portions of the ferrules 21 and 2b into the sleeve 3. The end of each of the ferrules 21 and 2b inserted in the sleeve 3 is polished into a predetermined shape (e.g., a hemispherical shape), so that the tip ends of the optical fibers 1a and 1b can be easily brought into contact, and a stable low-loss connection can be realized. Further, Japanese Unexamined Patent Publication Nos. 9(1997)-221342, 2004-279495, and 5(1993)-181040 disclose further information about stable optical contact between optical components.
However, when light having a wavelength in the short wavelength range propagates through the optical fibers 1a and 1b in the above optical device of FIG. 7, contamination with organic materials is likely to occur. Therefore, in order to prevent characteristic deterioration caused by the contamination, for example, the organic materials are removed by UV-cleaning the tip ends of the optical fibers 1a and 1b after polishing the tip ends of the optical fibers 1a and 1b. 
Nevertheless, the present inventors have confirmed that when an optical contact is formed by removing the organic materials by UV (ultraviolet) cleaning and pressing together the tip ends of the optical fibers 1a and 1b, some reaction with oxides (such as SiO2 or quartz) contained in the optical fibers 1a and 1b can occur at the abutting portions of the optical fibers 1a and 1b, and the abutting portions of the optical fibers 1a and 1b can be fixed together with the reaction products. Therefore, when the ferrules 21 and 2b are pulled out from the sleeve 3 after the above reaction, the abutting portions of the optical fibers 1a and 1b can be damaged.
In addition, even after the end surfaces of the optical fibers are UV cleaned, the organic materials cannot be completely removed. Therefore, when light having a wavelength in the short wavelength range propagates through the optical fibers 1a and 1b connected by an optical contact, and the organic materials remain at the abutting portions of the optical fibers, the organic materials at the abutting portions are decomposed by the light, and reaction with the oxides contained in the optical fibers 1a and 1b can occur, and cause damage to the abutting portions of the optical fibers. When the end surfaces of the optical fibers are damaged, the optical loss becomes great even if the tip ends of the optical fibers 1a and 1b are arranged in contact again, so that desirable performance cannot be achieved, and the reliability of the optical device is lowered.